WASHINGTON—The Pentagon is planning to develop two new sea-based nuclear weapons to respond to Russia and China’s growing military capabilities, according to a sweeping Defense Department review of nuclear strategy.

Supporters of the Pentagon’s plan say it is time for the U.S. to update its nuclear forces to deal with changing threats some three decades after the end of the Cold War. Critics worry that the Pentagon’s search for more flexible nuclear options could lower the threshold for their use.

One weapon, which experts say could be deployed in about two years, is a “low yield” warhead for the Trident missile, which currently is deployed with more powerful warheads on the Navy’s submarines that carry ballistic missiles.

The U.S. also would pursue the development of a new nuclear-tipped sea-launched cruise missile, reintroducing a system that was retired from the American arsenal in 2010.

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The development of the two weapons is among a broad range of recommendations in the Pentagon’s Nuclear Posture Review, a major reassessment of the U.S. nuclear strategy and programs that was commissioned about a year ago by President
Donald Trump.

That strategy, which is expected to be formally unveiled later this month, has yet to be approved by the president. The Pentagon has dismissed an unclassified draft of the strategy, which was published last week by HuffPost, as “pre-decisional,” while more updated drafts are also circulating. But the plans to field the new nuclear systems have strong support in the Pentagon and are expected to go forward, according to people familiar with the review.

A major question at the heart of the Pentagon review is how to respond to military strategy and programs in Russia and China, which American officials say provide a more prominent role for nuclear weapons. In effect, the Pentagon argues that since adversaries have failed to follow the U.S. in de-emphasizing the role of nuclear weapons, Washington needs a greater range of nuclear options to counter its potential foes, especially for carrying out limited strikes.

“While the United States has continued to reduce the number and salience of nuclear weapons, others, including Russia and China, have moved in the opposite direction,” said a draft of the plan. “The United States must be capable of developing and deploying new capabilities, if necessary, to deter, assure, achieve U.S. objectives if deterrence fails, and hedge against uncertainty.”

A major concern for the Pentagon is a new Russian ground-launched cruise missile that American officials say violates the treaty banning intermediate-range missiles based on land, which was signed in 1987 by President
Ronald Reagan
and
Mikhail S. Gorbachev,
leader of the then-Soviet Union. Russia’s decision to develop and deploy that system is described by the review as part of a Russian doctrine that calls for threatening the limited use of nuclear weapons, or perhaps even carrying out a limited nuclear strike, to end a conventional war on terms favorable to the Kremlin.

By developing a new American “low yield” system, the Pentagon review argues the U.S. will have more credible options to respond to Russian threats without using more powerful strategic nuclear weapons, which the Kremlin may calculate Washington would be reluctant to use for fear of unleashing an all-out nuclear war. Because the new weapons it is proposing would be based at sea, the U.S. wouldn’t need the permission of other nations to deploy them and their deployment wouldn’t violate existing arms-control agreements.

The draft doesn’t precisely define what “low yield” nuclear weapons might be, but the new Trident system might have a warhead of one or two kilotons, compared with the current system which has an explosive yield that ranges from 100 kilotons to 455 kilotons, depending on the warhead it carries. By comparison, the U.S. nuclear bomb dropped on Hiroshima, Japan, at the end of World War II was about 15 kilotons.

Critics have assailed the Pentagon’s review, arguing that it may bring about the very situation the Defense Department says it wants to avoid: a world in which the threshold for employing nuclear weapons is lowered.

“We should be doing everything to reduce the risk that nuclear weapons are going to be used, not expanding the ambiguity of when we might use nuclear weapons,” said
Jon Wolfsthal,
who served as a senior official for arms control on President
Barack Obama’s
National Security Council.

Bruce G. Blair,
a scholar at Princeton University who has argued for the abolition of nuclear weapons, said the Pentagon should be looking for ways to strengthen its cyber and conventional military capabilities instead of searching for new nuclear options, especially since the Russian may opt to use its new ground-launched cruise missile with a nonnuclear warhead.

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North Korea's launch of a missile that flew over Japanese territory has prompted intensified military activity by the U.S. and its allies in the Pacific. The WSJ's Gerald F. Seib explains what the heavier presence means for the standoff between Washington and Pyongyang. Photo: AP (Originally published Sept. 1, 2017)

The review has also drawn support, particularly from conservative quarters. “This is not about making weapons more usable; this is about strengthening deterrence so that nuclear weapons are not used in the first place,” said
Robert Joseph,
a senior national security official in the George W. Bush administration. “We have to think what would be credible in Russian eyes.”

While the review calls for “pursuing” a new sea-launched cruise missile, it notes there are some circumstances in which the Trump administration might shelve the program: a decision by Russia to fix its alleged violation of the 1987 treaty banning U.S. and Russian land-based intermediate-range missiles and also reduce its formidable arsenal of tactical nuclear weapons.

Russia and China aren’t the only threats cited in the nuclear review. It also asserts that upgrading the U.S. nuclear arsenal will add to the country’s ability to deter North Korean aggression.

“North Korea relies on hardened and deeply buried facilities to secure the Kim regime and its key military and command and control capabilities,” the review says. “Consequently, the United States will continue to field a range of conventional and nuclear capabilities able to hold such targets at risk.”

Despite the debate over the proposed “low yield” Trident missile and sea-launched cruise missile, many of the other weapons recommended by the review also were advocated by the Obama administration, including the development of a new strategic bomber and an air-launched cruise missile.

Paying for all of the missile and bomber programs may be a challenge. The review says carrying out the nuclear modernization and operating the systems will require, at most, 6.4% of the Defense Department budget, up from 2% to 3% today. If the Pentagon doesn’t secure the spending increases it anticipates, this could heighten the competition between nuclear and nonnuclear programs for budgetary resources. The development of nuclear warheads is funded by the Energy Department.